Single amino acid replacements in RocA disrupt protein-protein interactions to alter the molecular pathogenesis of group a streptococcus

Paul E. Bernard, Amey Duarte, Mikhail Bogdanov, James M. Musser, Randall J. Olsen

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Group A Streptococcus (GAS) is a human-specific pathogen and major cause of disease worldwide. The molecular pathogenesis of GAS, like many pathogens, is dependent on the coordinated expression of genes encoding different virulence factors. The control of virulence regulator/sensor (CovRS) two-component system is a major virulence regulator of GAS that has been extensively studied. More recent investigations have also involved regulator of Cov (RocA), a regulatory accessory protein to CovRS. RocA interacts, in some manner, with CovRS; however, the precise molecular mechanism is unknown. Here, we demonstrate that RocA is a membrane protein containing seven transmembrane helices with an extracytoplasmically located N terminus and cytoplasmically located C terminus. For the first time, we demonstrate that RocA directly interacts with itself (RocA) and CovS, but not CovR, in intact cells. Single amino acid replacements along the entire length of RocA disrupt RocA-RocA and RocA-CovS interactions to significantly alter the GAS virulence phenotype as defined by secreted virulence factor activity in vitro and tissue destruction and mortality in vivo. In summary, we show that single amino acid replacements in a regulatory accessory protein can affect protein-protein interactions to significantly alter the virulence of a major human pathogen.

Original languageEnglish (US)
Article numbere00386-20
JournalInfection and Immunity
Issue number11
StatePublished - Oct 19 2020


  • Accessory protein
  • Group A streptococcus
  • Molecular pathogenesis
  • Protein-protein interactions
  • RocA
  • SCAM™
  • Streptococcus pyogenes/genetics
  • Humans
  • Virulence
  • Myositis/metabolism
  • Cloning, Molecular
  • Fasciitis, Necrotizing/metabolism
  • Female
  • Bacterial Proteins/chemistry
  • Protein Interaction Domains and Motifs
  • Binding Sites
  • Genetic Vectors/chemistry
  • Amino Acid Sequence
  • Gene Expression
  • Streptococcal Infections/metabolism
  • Protein Structure, Secondary
  • Escherichia coli/genetics
  • Trans-Activators/chemistry
  • Animals
  • Repressor Proteins/chemistry
  • Survival Analysis
  • Protein Binding
  • Mice
  • Mutation
  • Gene Expression Regulation, Bacterial
  • Amino Acid Substitution
  • Histidine Kinase/chemistry

ASJC Scopus subject areas

  • Infectious Diseases
  • Parasitology
  • Microbiology
  • Immunology


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